The present invention relates to a method and an apparatus for analyzing constituents contained in a breath sample by means of gas chromatograph.
There is conventionally available an apparatus for analyzing a breath sample based on detection of alcohol. On the other hand, analysis of constituents of a sample by the use of a gas chromatograph is popularly applied. The conventional chromatograph is used by researchers or engineers well versed in handling of the equipment. There is available no apparatus for automatically starting a gas chromatograph, analyzing and testing a sample, and then completing. For many of the users, therefore, the conventional chromatographic analysis apparatus is hard to use.
There is known no apparatus serving for clinical tests in the medical area by analyzing breath constituents. A breath analyzing apparatus for such medical tests should preferably be easily and automatically used by a test operator.
The present invention has an object to provide breath analyzing apparatus and method for analyzing a breath sample by means of a gas chromatographic column.
Another object of the invention is to provide breath analyzing apparatus and method which permit automatic and easy breath analysis of a low-concentration constituent such as pentane.
Further, another object of the invention is to provide breath analyzing apparatus and method which permit analysis of low-concentration constituents and high-concentration constituents by the use of a single main column and a detector.
Further, another object of the invention is to provide breath analyzing method and apparatus which permit perfect automation of start processing until the analyzing apparatus is ready to analyze.
Further, another object of the invention is to provide breath analyzing method and apparatus which permit perfect automation of shutdown processing upon completion of analysis and until supply of a carrier gas is discontinued.
Further, another object of the invention is to provide breath analyzing method and apparatus which permit automatic testing of deterioration of the column.
Furthermore, the present invention has an object to provide a breath analyzing method and a compact apparatus for the application thereof, which permit automation of various steps, completion of analysis in a shorter period of time of analysis and is easy to use in the area of clinical testing having needs different from those of laboratories.
Another object of the invention is to provide breath analyzing apparatus and method for carrying out measurement of a room interior environment, detection of a narcotic drug in vivo, and investigation of a cause of fire.
To achieve these objects of the invention, the apparatus of the invention comprises desorbing means for desorbing a breath sample absorbed into an absorbent sample tube, a chromatographic precolumn for passing the breath sample desorbed from the absorbent sample tube in a retention time prescribed for each constituent, a chromatographic main column for passing the breath sample having passed through the precolumn, in a retention time prescribed for each constituent, a detector for detecting constituents having passed through the main column, and a data processor for generating a chromatograph for the constituents detected by the detector. As a result of presence of the precolumn, when there are two constituents having different retention times, there remains, after passage of one constituent, for example pentane, through the main column, the other constituent such as hexane in the precolumn, thus permitting earlier completion of analysis by purging the main column and the precolumn. Presence of the desorbing means permits satisfactory detection of low-concentration constituents contained in the breath such as pentane, dimethyl sulfide and isoprene.
Further, the apparatus of the invention comprises a sample receiving tube for receiving the exhaled breath sample, a sample loop for aspirating a prescribed quantity of breath sample from the sample receiving tube, and a sample valve which connects the sample loop and the main column when a breath sample is aspirated into the sample loop. This makes it possible to sample a high-concentration constituent in the breath such as acetone directly from the sample receiving tube and analyze the sampled constituent by means of the main column.
The apparatus of the invention further comprises a standard gas bottle for supplying a standard gas, and a standard gas valve which connects the standard gas bottle and the sample loop when testing sensitivity of said-column. This permits automatic testing of the column.
In a preferred embodiment, the apparatus of the invention comprises an interface having various buttons and a controller controlling start, analysis, testing and shutdown of the apparatus in response to an instruction to the interface.
In another preferred embodiment, there is disclosed a method necessary for separating isoprene and pentane by the use of the foregoing apparatus.